Description: 72 aircraft - 29 Lancasters, 22 Halifaxes, 21 Stirlings - were dispatched on an interesting raid. All the aircraft were provided by No 8 Group and it was really a mass H2S trial. 33 of the aircraft carried markers or flares, the remaining aircraft acting as the bombing force, although the marker aircraft also bombed. The marking and bombing were very accurate and the whole raid lasted less than 10 minutes. Photographic reconnaissance showed that much damage was done to railway installations in Münster as well as to housing areas. Unfortunately the raid was expensive for the small force involved; 5 aircraft - 2 Halifaxes, 2 Lancasters and 1 Stirling - were lost, 6.9 per cent of the aircraft involved.